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Ask the experts Andrew Sachs, vice president of product management at Volicon Addressing lingering loudness challenges Why and how has loudness become such prominent issue? T he loudness of the television commercials aired between program segments has been the source of consumer complaints and subsequent regulatory action in countries around the world. These complaints stem from the networks’ and advertisers’ economic incentives for consumers to notice loud advertisers, paired with the expanded dynamic range available with digital audio delivery. Though audio levels remain within a technically acceptable range, advertising may be delivered at higher levels so that consumers notice the louder ads. Because the factors contributing to perceived loudness are more complex than previous peak metering, the industry took action. The ITU created study groups that attempted to objectify the subjective perception of loudness. These study groups helped to develop ITU-R BS.1770 (algorithms for measuring audio program loudness and true-peak audio level), which dealt with spatial, frequency, and power based components to create an objective measurement of loudness. 48 | TV-BAY MAGAZINE: ISSUE 83 NOVEMBER 2013 The EBU PLOUD groups added to the ITU’s efforts by incorporating temporal components (level-based gating) that prevented periods of silence from lowering the loudness measurement. This level-based gating technique would cause a dialog track to measure a consistent loudness regardless of whether there were pauses (silence) between speech elements in the track. The ATSC stayed on a different path by using the dialog (anchor element) power as the indication of the loudness of program in which speech is present. Not coincidentally, this technique is also resistant to the presence of pauses between speech elements. Additionally, many organizations including EBU and ATSC addressed the difference in loudness perception that can be created by “improperly mixing” surround (5.1) content so that it is experienced relatively more loudly (up to 3dB) when consumed as a stereo downmix. As 85 percent of HD surround content is consumed on stereo speakers, this “stereo downmix” measurement is the critical measurement for 5.1-delivered content. This “improper mixing” technique could be easily abused by advertisers to deliver ads that are compliance in the 5.1 measurement but are up to 3dB when consumed as a downmix. Practical downstream measurement techniques and tools (e.g., at the output of the set-top box) were not widely utilized. Complicating elements such as content boundary alignments, compression artifacts, and non- automated measurement techniques made it very difficult for broadcasters or networks to look at the end of the broadcast pipe and verify compliance. Without proper measurement techniques and practical widely accepted tolerances, there is bound to be organizational friction dealing with this ambiguity. While loudness is very easy to legislate (e.g., “commercials shall not be louder than the surrounding program”), the incentives of broadcasters remain aligned with their advertisers. This, paired with the evolving loudness measurement basis and underutilized downstream measurement techniques, has caused loudness to become a very prominent issue. It is easy to spot but hard to verify. How are broadcasters and other service providers successfully incorporating loudness measurement into their workflows? Loudness measurement is typically incorporated into broadcasters’ workflows through several different mechanisms. File-based workflows have file quality assurance (QA) tools that measure asset loudness as one of the many QA elements they perform. If levels are off-target, content is rejected or audio is typically remixed at a different level to match the station target level. While live event loudness is more challenging because of the dynamics of the event, these events typically benefit from the presence of sound engineers who will mix and level audio according to their ears and to real-time loudness meters. Many recommended practices have wider tolerances for live events because of these challenges. Finally, broadcasters and networks are measuring the compressed downstream delivered by recording the compressed stream and using automation log records to find the asset boundaries. A loudness meter with content recording then references the content recording and boundaries to measure every asset broadcast for the day. This serves as a final quality check and allows broadcasters to catch holes in loudness control processes while easily delivering on compliance requests. Loudness control devices were initially installed by broadcasters as sort of a hammer to ensure compliance to loudness legislation. However, as complaints mount regarding the detrimental effect these control devices have on the content experience and as the content supply chain evolves with higher levels of loudness compliance, these control devices are being disabled or taken out entirely. How does a monitoring and logging system actually perform loudness measurement? One of the primary benefits of using a monitoring and logging system equipped with loudness measurement and reporting functions is that the system can capture and store an array of individual loudness measurements,